位置: 编程技术 - 正文

The graphics pipeline ,Open GL 渲染管线

编辑:rootadmin

推荐整理分享The graphics pipeline ,Open GL 渲染管线,希望有所帮助,仅作参考,欢迎阅读内容。

文章相关热门搜索词:,内容如对您有帮助,希望把文章链接给更多的朋友!

来源: Ever since the early days of real-time 3d, the triangle has been the paintbrush with which scenes have been drawn. Although modern GPUs can perform all sorts of flashy effects to cover up this dirty secret, underneath all the shading, triangles are still the medium in which they work. The graphics pipeline that OpenGL implements reflects this: the host program fills OpenGL-managed memory buffers with arrays of vertices; these vertices are projected into screen space, assembled into triangles, and rasterized into pixel-sized fragments; finally, the fragments are assigned color values and drawn to the framebuffer. Modern GPUs get their flexibility by delegating the “project into screen space” and “assign color values” stages to uploadable programs called shaders. Let’s look at each stage in more detail:

The vertex and element arrays A rendering job starts its journey through the pipeline in a set of one or more vertex buffers, which are filled with arrays of vertex attributes. These attributes are used as inputs to the vertex shader. Common vertex attributes include the location of the vertex in 3d space, and one or more sets of texture coordinates that map the vertex to a sample point on one or more textures. The set of vertex buffers supplying data to a rendering job are collectively called the vertex array. When a render job is submitted, we supply an additional element array, an array of indexes into the vertex array that select which vertices get fed into the pipeline. The order of the indexes also controls how the vertices get assembled into triangles later on.

Uniform state and textures A rendering job also has uniform state, which provides a set of shared, read-only values to the shaders at each programmable stage of the pipeline. This allows the shader program to take parameters that don’t change between vertices or fragments. The uniform state includes textures, which are one-, two-, or three-dimensional arrays that can be sampled by shaders. As their name implies, textures are commonly used to map texture images onto surfaces. They can also be used as lookup tables for precalculated functions or as datasets for various kinds of effects.

The vertex shader The GPU begins by reading each selected vertex out of the vertex array and running it through the vertex shader, a program that takes a set of vertex attributes as inputs and outputs a new set of attributes, referred to as varying values, that get fed to the rasterizer. At a minimum, the vertex shader calculates the projected position of the vertex in screen space. The vertex shader can also generate other varying outputs, such as a color or texture coordinates, for the rasterizer to blend across the surface of the triangles connecting the vertex.

Triangle assembly

The graphics pipeline ,Open GL 渲染管线

The GPU then connects the projected vertices to form triangles. It does this by taking the vertices in the order specified by the element array and grouping them into sets of three. The vertices can be grouped in a few different ways:

Take every three elements as an independent triangle Make a triangle strip, reusing the last two vertices of each triangle as the first two vertices of the next Make a triangle fan, connecting the first element to every subsequent pair of elements The diagram shows how the three different modes behave. Strips and fans both require only one new index per triangle in the element array after the initial three, trading the flexibility of independent triangles for extra memory efficiency in the element array.

Rasterization

The rasterizer takes each triangle, clips it and discards parts that are outside of the screen, and breaks the remaining visible parts into pixel-sized fragments. As mentioned above, the vertex shader’s varying outputs are also interpolated across the rasterized surface of each triangle, assigning a smooth gradient of values to each fragment. For example, if the vertex shader assigns a color value to each vertex, the rasterizer will blend those colors across the pixelated surface as shown in the diagram.

The fragment shader The generated fragments then pass through another program called the fragment shader. The fragment shader receives the varying values output by the vertex shader and interpolated by the rasterizer as inputs. It outputs color and depth values that then get drawn into the framebuffer. Common fragment shader operations include texture mapping and lighting. Since the fragment shader runs independently for every pixel drawn, it can perform the most sophisticated special effects; however, it is also the most performance-sensitive part of the graphics pipeline.

Framebuffers, testing, and blending A framebuffer is the final destination for the rendering job’s output. In addition to the default framebuffer OpenGL gives you to draw to the screen, most modern OpenGL implementations let you make framebuffer objects that draw into offscreen renderbuffers or into textures. Those textures can then be used as inputs to other rendering jobs. A framebuffer is more than a single 2d image; in addition to one or more color buffers, a framebuffer can have a depth buffer and/or stencil buffer, both of which optionally filter fragments before they are drawn to the framebuffer: Depth testing discards fragments from objects that are behind the ones already drawn, and stencil testing uses shapes drawn into the stencil buffer to constrain the drawable part of the framebuffer, “stencilling” the rendering job. Fragments that survive these two gauntlets have their color value alpha blended with the color value they’re overwriting, and the final color, depth, and stencil values are drawn into the corresponding buffers.

Conclusion That’s the process, from vertex buffers to framebuffer, that your data goes through when you make a single “draw” call in OpenGL. Rendering a scene usually involves multiple draw jobs, switching out textures, other uniform state, or shaders between passes and using the framebuffer’s depth and stencil buffers to combine the results of each pass. Now that we’ve covered the general dataflow of 3d rendering, we can write a simple program to see how OpenGL makes it all happen. Throughout the course of this tutorial, I’d love to get your feedback—let me know if it’s helping you or if anything doesn’t make sense.

Following the pipeline 1.PassingDatatotheVertexShaderThevertexshaderisthefirstprogrammablestageintheOpenGLpipelineandhasthedistinctionofbeingtheonlymandatorystageinthepipeline.VertexAttributesInGLSL,themechanismforgettingda

Tutorial 4: Shaders 本文源自:

FreeGLUT Tips: 详解 glutInit 的入口参数 问题前文我们遇到的问题是,如何正确地给glutInit()这个函数传递一个正确的入口参数,使它能够正确地初始化OpenGL环境。假设大家都在使用VisualC++。当

标签: The graphics pipeline ,Open GL 渲染管线

本文链接地址:https://www.jiuchutong.com/biancheng/369418.html 转载请保留说明!

上一篇:openGL4.X 深度测试(depth testing) framebuffer中(opengl 4.2)

下一篇:Following the pipeline

  • 附加税的税率表
  • 资金预算表编制依据
  • 车辆租赁费发票备注栏怎么写
  • 银行的划分标准
  • 企业所得税几大税种
  • 银行回单日期晚于做账日期
  • 长期待摊费用属于无形资产吗
  • 营改增的会计处理及其对财务的影响
  • 企业录用失业人员有税收优惠吗
  • 增值税过期未抵扣
  • 应交税费明细科目设置
  • 小规模纳税人工程服务的增值税率
  • 上个月有留抵税这个月怎么结转税金
  • 其他综合收益影响递延所得税负债吗
  • 材料报废的会计处理(一般纳税人)
  • 税前利润弥补亏损
  • 无法加载响应数据 对于预检请求没有可显示的内容
  • 企业向个人的借款合同
  • 怎么做才能让电脑里自动翻译成中文
  • 为什么浏览器自动打开
  • PHP:pg_connection_status()的用法_PostgreSQL函数
  • 微信公众号实名认证怎么更改
  • sk是什么软件的缩写
  • 实收资本的会计编码
  • 红字专用发票是红色的吗
  • vue sha256加密
  • php标准数据类型共有四种
  • php知识点汇总与解答
  • 盘盈的存货账务怎么处理
  • ps位图矢量化
  • jwt中的jti
  • 未分配利润为负数怎么调整
  • 研发支出什么时候转管理费用
  • 应收账款能想到什么
  • 域名费用怎么交
  • MySQL查看最大连接数
  • SQL Server 使用 SET FMTONLY ON 获得表的元数据
  • 编写脚本语言
  • centos编译运行c程序
  • 经营许可证需要多久时间
  • 劳务派遣人员保险
  • sql,server
  • 防伪码显示查询次数和时间
  • 工程奖金计入什么科目
  • 本月暂估入库,下月
  • 收据和收款收据的法律效力
  • 为什么规定视同销售?
  • 施工赔偿款怎么记账
  • 在途物资材料采购原材料的区别
  • 企业注销未分配是从注册开始吗
  • 几个比较重要的家风
  • js操作剪切板
  • sql触发器语句
  • win7 64位系统如何查看计算机名称为了应付某一操作
  • u盘启动pe装机工具怎么用
  • win7怎样关闭u盘保护功能
  • alp是什么文件
  • SpySub.exe - SpySub是什么进程
  • pniopcac.exe是什么
  • win7系统浏览器打不开网页怎么办
  • 有没有免费的win10
  • bat批处理视频教程
  • Unity3D游戏开发pdf
  • javascript基于
  • jquery插件怎么用到自己的网站
  • 怎么设置网页就用指定浏览器
  • apktool修改包名
  • 合并一个文件夹下多个工作簿
  • android设计模式总结
  • Unity3D中Enabled、Destroy与Active的区别
  • 用python编写
  • 手把手教你把币从交易所提到钱包
  • jquery常用操作
  • js命名函数
  • 付姓人数
  • 胡世军简历年龄多大
  • 客货两用车应如何运输
  • 税收助力双创
  • 国税地税什么时候申报
  • 个人利息收入属于什么收入
  • 免责声明:网站部分图片文字素材来源于网络,如有侵权,请及时告知,我们会第一时间删除,谢谢! 邮箱:opceo@qq.com

    鄂ICP备2023003026号

    网站地图: 企业信息 工商信息 财税知识 网络常识 编程技术

    友情链接: 武汉网站建设